Visual Basic中的Modbus RTU(vb.net)

问题描述

大家好，
我正试图创建一个Modbus RTU主程序...我发现了很多代码，但是使用C#.当我尝试在Visual Basic(vb.net 2010)中进行转换时，它不起作用... PLC无法应答.
我认为serialport.write(< byte> ;,< int> ;,< int>)函数存在问题.有人可以帮助我吗?

遵循代码

 公共 功能 SendFc3( ByVal 地址 As  字节， ByVal 开始 As   UShort ， ByVal 注册 As   UShort ， ByRef 值 As  简短())

         Dim 标志 As  布尔值 = 错误
        ' 确保端口已打开:
        如果(Sp.IsOpen)然后

            ' 清除输入/输出缓冲区:
            Sp.DiscardOutBuffer()
            Sp.DiscardInBuffer()
            ' 功能3请求始终为8个字节:
             Dim 消息 As   Byte ()= 新建 字节( 7 ){}
            ' 功能3响应缓冲区:
             Dim 响应 As   Byte ()= 新建 字节((< 5  +  2  *寄存器)- 1 ){}
            ' 构建传出的Modbus消息
            BuildMessage(地址， CByte ( 3 )，开始，寄存器，消息)
            ' 将Modbus消息发送到串行端口:
            尝试

                sp.Write(message， 0 ，message.Length)
                ' 评估消息:
                如果(GetResponse(响应，sp，值))然后
                    标志= 正确
                结束 如果

            捕获错误 As 异常
                modbusStatus = " 读取事件出错:"  + err.Message
                标志= 错误
            结束 尝试
        其他

            modbusStatus = " 串行端口未打开" 
            标志= 错误
        结束 如果
        返回标志

    结束 功能 

 公共  Sub  BuildMessage( ByVal 地址 As  字节， ByVal 类型 As  字节， ByVal 开始 As   UShort ， ByVal 注册 As   UShort ， ByRef 消息 As  字节())

       ' 接收CRC字节的数组:
        Dim  CRC  As   Byte ()= 新建 字节( 2 ){}

       message( 0 )= 字节 .Parse(地址)
       message( 1 )= 字节 .Parse(类型)
       message( 2 )= 字节.Parse(开始>>  8 )
       message( 3 )= 字节 .Parse(开始)
       message( 4 )= 字节.Parse(注册>>  8 )
       message( 5 )= 字节 .Parse(寄存器)

       GetCRC(消息，CRC)
       message(message.Length- 2 )= 字节 .Parse( 84 )'  CRC(0)
       message(message.Length- 1 )= 字节 .Parse( 10 )'  CRC(1)

   结束 子 

 公共 功能 GetResponse( ByRef 响应 As  字节()， ByRef  spModbus  As  SerialPort， ByRef 值 As  简短())

         Dim  i  As  整数 =  0 
        '  Thread.Sleep(300)
        同时(spModbus.BytesToRead<>  0 )
            response(i)= 字节 .Parse(spModbus.ReadByte())
            '  Thread.Sleep(200)
            我+ =  1 
            '  Application.DoEvents()
        结束 同时

        ' 验证消息
        如果(CheckResponse(response))然后

            '  Ritorno il valore dei registri richiesti 
            对于 i =  0  要((响应.Length- 5 )/ 2 )- 1 

                response(i)= response( 2  * i +  3 )
                响应(i)<< =  8 
                响应(i)+ =响应( 2  * i +  4 )
                值(i)=响应( 2  * i +  3 )
                values(i)<< =  8 
                值(i)+ =响应( 2  * i +  4 )

            下一步

            返回 真实

        其他

            返回 错误

        结束 如果

    结束 功能 

感谢

解决方案

Hi all,
i''m tring to create a modbus rtu master program... i found a lot of code but in C#. when i try to convert it in visual basic (vb.net 2010) it doesn''t work... the PLC doesn''t answer.
i think that there is a problem with the serialport.write(<byte>, <int>, <int>) function. someone can help me?

follow the code

Public Function SendFc3(ByVal address As Byte, ByVal start As UShort, ByVal registers As UShort, ByRef values As Short())

        Dim flag As Boolean = False
        'Ensure port is open:
        If (Sp.IsOpen) Then

            'Clear in/out buffers:
            Sp.DiscardOutBuffer()
            Sp.DiscardInBuffer()
            'Function 3 request is always 8 bytes:
            Dim message As Byte() = New Byte(7) {}
            'Function 3 response buffer:
            Dim response As Byte() = New Byte((5 + 2 * registers) - 1) {}
            'Build outgoing modbus message
            BuildMessage(address, CByte(3), start, registers, message)
            'Send modbus message to Serial Port:
            Try

                sp.Write(message, 0, message.Length)
                'Evaluate message:
                If (GetResponse(response, sp, values)) Then
                    flag = True
                End If

            Catch err As Exception
                modbusStatus = "Error in read event: " + err.Message
                flag = False
            End Try
        Else

            modbusStatus = "Serial port not open"
            flag = False
        End If
        Return flag

    End Function

Public Sub BuildMessage(ByVal address As Byte, ByVal type As Byte, ByVal start As UShort, ByVal registers As UShort, ByRef message As Byte())

       'Array to receive CRC bytes:
       Dim CRC As Byte() = New Byte(2) {}

       message(0) = Byte.Parse(address)
       message(1) = Byte.Parse(type)
       message(2) = Byte.Parse(start >> 8)
       message(3) = Byte.Parse(start)
       message(4) = Byte.Parse(registers >> 8)
       message(5) = Byte.Parse(registers)

       GetCRC(message, CRC)
       message(message.Length - 2) = Byte.Parse(84) 'CRC(0)
       message(message.Length - 1) = Byte.Parse(10) 'CRC(1)

   End Sub

Public Function GetResponse(ByRef response As Byte(), ByRef spModbus As SerialPort, ByRef values As Short())

        Dim i As Integer = 0
        'Thread.Sleep(300)
        While (spModbus.BytesToRead <> 0)
            response(i) = Byte.Parse(spModbus.ReadByte())
            'Thread.Sleep(200)
            i += 1
            'Application.DoEvents()
        End While

        'Verifico il messaggio
        If (CheckResponse(response)) Then

            'Ritorno il valore dei registri richiesti
            For i = 0 To ((response.Length - 5) / 2) - 1

                response(i) = response(2 * i + 3)
                response(i) <<= 8
                response(i) += response(2 * i + 4)
                values(i) = response(2 * i + 3)
                values(i) <<= 8
                values(i) += response(2 * i + 4)

            Next

            Return True

        Else

            Return False

        End If

    End Function

Thanks

解决方案

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